A known window shade mechanism specifically adapted for aircraft windows utilizes cables and pulleys. A slidable actuator must be manually moved to operate the window shade. See U.S. Pat. No. 5,082,043. Reliance on manual operation is inconvenient because, for example, all the window shades on the aircraft cannot be operated simultaneously by one person. Also, the parts are particularly vulnerable to malfunction. Moreover, many components are required, and this reduces reliability while adding to the cost.
Another known approach provides a motor which is fixed in the window and operates the shade with cables and pulleys. See U.S. Pat. Nos. 5,515,898 and 4,998,576. However, this approach also requires numerous components which can only be manufactured, assembled and installed at considerable cost. Reliability is also compromised by the inclusion of so many parts.
Yet another approach attaches a motor to the lower bar, or rail, of the shade, and the motor moves along with the shade as it is extended and compressed. See U.S. Pat. No. 4,807,686. However, this approach also utilizes numerous components which raise the cost of manufacture and lower the reliability.